Abstract

Text messaging, also known as short message services (SMS), is a burgeoning innovation area showing promise in eliciting health behavior changes. This dissertation details two intervention trials that each comparatively tests the efficacy of different text message sets intended to improve behaviors.

In light of pervasive road traffic injuries amongst young men in Tanzania, the first intervention tested messaging strategies aimed at increasing helmet wearing amongst commercial motorcycle taxi drivers. Participants (N=391) were randomized to receive either: 1) social norming messages emphasizing society’s positive stance on helmets; 2) fear appeal messages emphasizing the dangers of riding without helmets, or 3) control messages. After 6-weeks, the odds of drivers reporting wearing their helmet “on every trip” was 1.58 times higher in the social norming group than amongst controls, though this difference was not significant after accounting for multiple hypothesis testing. There was little difference between fear appeal recipients and controls.

In light of China’s excessive caesarean section rate of up to 54.9%, the second trial tested messaging strategies aimed at reducing unnecessary caesareans. This quasi-randomized trial assigned pregnant women (N= 4,375) to receive one of four message sets: 1) Limited “Basic” messages, 2) A set primarily regarding Care-Seeking, 3) A set primarily regarding good prenatal Home Practices, or 4) All Texts. Amongst women that acknowledged receiving program texts, care-seeking messages alone were associated with reduced odds of caesarean delivery (OR=0.71, p=.045). Assignment to receive All Texts was associated with strongly reduced odds (OR = 0.65, p=0.008).

Last, an observational study utilizing the Xi’an data investigated the association newborns being born small for gestational age (SGA) and women’s levels of family support. Adjusted logistic regression found that high support was associated with reduced odds of SGA (OR =0.681 p=.013). Mediation analysis suggested this association was at least partially mediated by better nutrition supplementation and more moderate exercise.

These results suggest SMS interventions may be useful tools in eliciting behavior change surrounding helmet wearing and mode of delivery. Some message types may outperform others, and family support may be a useful leverage point. Further investigation is warranted.